Milford sewer customers could soon see a small hike in their monthly utility bills.

City Council is expected to vote Monday on a 7-cent rate increase on customers who use more than 1,000 gallons a month.

If approved, Milford’s sewer rate for usage greater than 1,000 gallons a month would increase 2.6 percent from $2.71 per 1,000 gallons to $2.78 per 1,000 gallons. Customers would continue to be billed a $10 per month charge for usage under 1,000 gallons.

City officials say the revenue from the proposed sewer rate hike would cover the $51,000-a-year debt service on an emergency back-up pipe that would used to continue feeding the city’s raw sewage to the Kent County Regional Wastewater Treatment Facility in Frederica if the main line that runs under Route 1 were to fail.

Such a failure occurred in December 2008, when a chunk of concrete in the line eventually created enough pressure to cause the 12-inch pipe to burst under Route 1, just east of Milford. Having nowhere else for Milford’s sewage to go, county officials opted to direct 1.6 million gallons of wastewater into the Mispillion River before the break could be repaired.

“That break put an emphasis on the need for an alternate, parallel route, and fortunately, Harrington was already in the process of moving toward tying its sewer into the county system,” Kent County Public Works Director Hans Medlarz said. “That gave the county an opportunity to tie an emergency back-up for Milford’s system into the Harrington line.”

Harrington voters approved that city’s link to the county service lines in May, 2010 and Medlarz said the project, including the Milford back-up, was completed in 2011.

Medlarz said the back-up line is tested every six months, but otherwise would not be used on a regular basis.

Yet, according to the service agreement between Milford and Kent County, the city is on the hook for a $1.3 million share of the project, which is to be paid off over the next 40 years.

“The rate increase associated with this really won’t end up being a lot of money for the average sewer customer,” Milford City Manager Richard Carmean said. “I know that personally at my house, a lot of months, it will end up being less than an extra $1 month for me.”

If approved by City Council on Monday, the proposed sewer rate hike would take effect on March 21, meaning customers would first see the increase in their April bills.

“This back-up pipe is actually a great thing for the city and the environment,” Carmean said. “When we can’t ship our sewage through the pipe, we would have to truck up there to the county facility, which can be very expensive – a lot more expensive than 7 cents.”